I'm having problems with loading car setups in my game. When I download setups most of them work but some don't. When they don't work the game just reverts to the 'default' setup.

Upon further inspection I noticed that all the setup files that don't work are 272 bytes in size, when I look in the properties of the file.
My own setups, and most of the downloaded setups are all 264 bytes in size and they work fine.

The 272 byte setups are long format which is used by all of the mods and the 1967 1.3 patch. These will not load into standard GPL 1.2
The 264 byte setup format is what GPL originally shipped with. These can be loaded by all versions of GPL.